1GETDTABLESIZE(3)           Linux Programmer's Manual          GETDTABLESIZE(3)
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NAME

6       getdtablesize - get file descriptor table size
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SYNOPSIS

9       #include <unistd.h>
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11       int getdtablesize(void);
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13   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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15       getdtablesize():
16           Since glibc 2.20:
17               _DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
18           Glibc 2.12 to 2.19:
19               _BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
20           Before glibc 2.12:
21               _BSD_SOURCE || _XOPEN_SOURCE >= 500
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DESCRIPTION

24       getdtablesize()  returns the maximum number of files a process can have
25       open, one more than the largest possible value for a file descriptor.
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RETURN VALUE

28       The current limit on the number of open files per process.
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ERRORS

31       On Linux, getdtablesize() can return any of the  errors  described  for
32       getrlimit(2); see NOTES below.
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ATTRIBUTES

35       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
36       tributes(7).
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38       ┌────────────────────────────────────────────┬───────────────┬─────────┐
39       │Interface                                   │ Attribute     │ Value   │
40       ├────────────────────────────────────────────┼───────────────┼─────────┤
41       │getdtablesize()                             │ Thread safety │ MT-Safe │
42       └────────────────────────────────────────────┴───────────────┴─────────┘
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CONFORMING TO

45       SVr4, 4.4BSD (the getdtablesize() function first appeared  in  4.2BSD).
46       It  is  not  specified  in POSIX.1; portable applications should employ
47       sysconf(_SC_OPEN_MAX) instead of this call.
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NOTES

50       The glibc version of getdtablesize() calls getrlimit(2) and returns the
51       current RLIMIT_NOFILE limit, or OPEN_MAX when that fails.
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SEE ALSO

54       close(2), dup(2), getrlimit(2), open(2)
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COLOPHON

57       This  page  is  part of release 5.13 of the Linux man-pages project.  A
58       description of the project, information about reporting bugs,  and  the
59       latest     version     of     this    page,    can    be    found    at
60       https://www.kernel.org/doc/man-pages/.
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64Linux                             2021-03-22                  GETDTABLESIZE(3)
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